1. Field of the Invention
The present invention relates to a condenser microphone used in a mobile communication terminal. More particularly, the present invention relates to an electret condenser microphone which reinforces electrostatic discharge protection and noise isolation by adding a series of components in the electret condenser microphone.
2. Description of the Related Art
Generally, in a condenser microphone used in a mobile communication terminal such as a smart phone, a PDA, a CDMA terminal and a GSM terminal, etc., sounds are received depending on quantity of electric charge varied according to a sound pressure and provided to a baseband codec through a Field-Effect Transistor (FET) as a differential type (which is one having both a positive terminal and a negative terminal).
However, in the above-mentioned condenser microphone, an external body is formed as a terminal of the differential, not a ground. Accordingly, when connecting to a device of the mobile communication terminal, noise flows in an input of the microphone due to a contact of a power supply line and a ground source.
In addition, as shown in FIG. 1, according to the related art condenser microphone, since only a Multi Layer Ceramic Capacity (MLCC) 11, which is a chip capacitor, and a FET 12 are provided on an internal PCB substrate 10, electrostatic discharge (ESD) protection is also poor.